Percussion tool



Augl, 1944-' c. s. WEYANDT 2,354,723

PERCUSSION TOOL Filed Deo. 12, -1941 `2 sheets-sheet 1 VIII/[IIIA INVENTOR Aug- 1, 1944- c. s. wEYAND-r I 2,354,723

PERCUSS SION TOOL Filed Dec. 12 1941 2 Sheets-Sheet 2 ATTORNE Patented Aug. 1, 1944 UNITED STATES PATENT lol-Flcla PERCUSSION TOOL Carl S. Weyandt, Homer City, Pa. ApplieationDecember 12, 1941, Serial No. 422,753

1 Claim.

The present invention relates to percussion tools, particularly of the type having a free armature reciprocated by spaced current impulses.

In such percussion tools there is generally provided a cylinder, barrel, or other structure of non-magnetic material, in which the armature, usually in the form of a piston, is reciprocated, the barrel being surrounded by laminations of magnetic material constituting a core about which is wound an/electrical conductor. Heretofore, in such percussion tools, various means have been proposed to secure the laminated magnetic core structure to the nonmagnetic barrel, as for example, clamping plates heldin place by screws, or wire bindings or circular rings. However, such means are not suitable for percussion tools having high impact energy, as the Vibrations and impact gradually loosens the binding for the laminated core, and as soon as one part becomes loose the whole structure soon disintegrates and becomes useless.

According to the present invention, the laminations of magnetic material are secured together in any suitable manner, as by rivets, to constitute a core unit, and the core units are secured to the barrel by welding them thereto. In a preferred embodiment of the invention particularly applicable to percussion tools which develop great impactive force, I provide side plates on the core units of a weldable steel alloy, by which the core units are welded to the barrel. I prefer to use non-magnetic stainless steel, particularly the 18:8 Variety for the barrel of the percussion tool, because such steel alloy is Wear-resistant, has

great strength to resist vibration, impact and shock, and to induced currents. The side plates of the core members preferably are made of a mild low carbon steel, or may be made of stainless steel, high manganese steel, or other weldable material, and as the barrel generally is of stainless steel or high manganese steel, I prefer to use stainless steel Welding rod in securing the laminations to the barrel. However, the barrel may be made of other non-magnetic material, for example, manganese steel or bronze, in which case the side laminations may be of like material or of any material weldable or capable of being brazed to the barrel. Structures made in accordance with the present invention have been found suitable for hammers and like tools wherein the piston may be impacted in one direction from 750 to 3600 times per minute, as a stable structure is provided. Furthermore, by providing a disicontinuous or interrupted weld in this construction induced currents and eddy current losses are reduced. The laminations being made substantially integral with the barrel, there is no opportunity for any part of the structure to become loosened from any other part, so that the structure is capable of resisting vibrations and impact to a high degree.

The invention will be described in detail in connection with the accompanying drawings, wherein a preferred embodiment of the invention is shown by way of example, and wherein,

Figure l is a vertical sectional View of a barrel and lamination assembly,

Figure 2 is an end view partly in section look'- ing toward the left of Figure 1,

Figure 3 is a fragmentary section taken on line III-III of Figure l,

Figure 4 is an enlarged sectional view of a detail,

Figure 5 is a plan view of a modification,

Figure 6 is a bottom View of a detail, 'K

Figure 7 is a partly diagrammatic View of a percussion tool assembly, and

Figure 8 is a wiring diagram for operation thereof.

Referring to the drawings, Figure '7, there lis shown a guide barrel I which is made of any suit.- able non-magnetic material, as for example, brass, bronze, manganese steel or stainless steel. I prefer to employ stainless steel for the barrel because I have found this material is highly wearresistant and has great strength to resist shocks and impact. A piston. Ia, is adapted to be reciprocated in the barrel by electromagnetic impulses developed in the core laminations 2, 3, 4 and 5 (Figure 1) about which are wound coils or solenoids 6 and 6a (Figure 7). In the modification shown in Figure 1, the barrel I has openings l, 8, 9 and I0 adapted to receive the pole faces I 2, I3, I4 and I5 respectively of the laminations 2, 3, 4 and 5, and the pole faces may be spaced a suitable distance from the internal diameter of the barrel to prevent contact with the piston. However, if desired, when a stainless steel barrel is employed, the pole faces may be substantially flush therewith.

The laminated structure 2 comprises an L- shaped member built up of a plurality of laminations I`I of high silicon steel or other magnetic material of low retentivity, with side plates I8 and I9 of a weldable metal, such as, for example, low carbon steel. Rivets 2| secure the k laminations and side plates together to provide a unitary structure. The laminated structures 3, 4 and 5 are similarly constructed with side plates of a weldable material, and need not be described in further detail.

In assembly, the electromagnet cores are placed in position with the barrel l, which may have flat exterior faces, with a portion extending through the openings 1, 8, 9 and l0, and they are secured in position by welding the side plates I8 and I9 to the barrel l, as indicated at 25. Cores 2 and 5 are also welded to the enlarged ends 26 and 21 of the barrel as indicated at 28. As an additional brace for the structure, blocks 29 of a weldable non-magnetic material are located in suitable recesses in the cores 2, 3, 4 and 5, and are welded in position at 3| and 32, as shown in Figure 4. A layer of suitable insulation 33 is then placed on the core and the windings then may be wrapped on the cores.

In the modication shown in Figure 5, there are two end series of L-shaped core members 35 and 31 and a middle T-shaped member 36, all of high silicon steel, providing two spaced sets of pole tips for a double wave actuated percussion tool, that is, one in which one rectified current wave impels the piston in one direction, and another rectied wave returns the piston. The core members are welded at their ends, as indicated at 38 and 39, to the barrel, and are also welded along the sides, as indicated at 4i, to the barrel. However, a space 42 preferably is provided to provide a break in the circuit and thus eliminate high induced currents in the core structure. The barrel in this modification, as well es ."n Figure 1, preferably is split, as at 43, to eliminate high induced currents therein. A layer of insulation material, preferably in the form of a cord or ribbon, is wound about the exterior of the core structure, and the wound structure then is impregnated with Bakelite varnish or other suitable binder. The insulating material thus provides a spool as shown in Figure l, upon which the wire conductor is wound, and the grooves- 45 form a keyway to prevent the winding from coming loose.

Referring to Figure 8, a plug 45 is connected to a suitable source of alternating current which passes through the wires 46 and 41 and through rectifiers 48 and 49, preferably of the dry disk type, and by wires l and 52 to a threeway plug 54, a common return 55 being provided. When plug 56 is connected to plug 54, connections are made at A, A', B, B' and R, R', respectively. One end of coil 6a is connected by wire 6l to the point B, while wire 62 leads from the other end of coil 6a through a switch 63 and a wire B4 connects switch 63 to point R. The end of coil 6 is connected by wire 65 to the point A.

In operation, one half wave from the alternating current source passes through rectifier 48 to coil li to actuate the piston la in one direction and the other half current wave of unlike polarity passes through rectifier 49 to coil 6a to actuate the piston in the opposite direction. Thus, in operating from a sixty cycle source, the piston impacts at each end of its stroke 3600 times per minute, and in operating from a twenty-five cycle source the piston would impact 1500 times per minute at each end. A suitable buffer is provided at the handle end of the piston stroke to cushion the impacts, and the tool at the opposite end of the stroke receives the impacts to perform useful work.

In a modification of my invention, in place of employing side plates of a weldable steel alloy, I employ a middle plate of sufficient thickness of a weldable steel alloy and secure the magnetic laminations thereto in any suitable manner, as by rivets, the core assembly being secured to the barrel by welding thereto.

The invention is not limited to the specific embodiments disclosed in this application, as various modications thereof may be made without departing from the spirit or scope of the invention.

What I claim as my invention and desire to secure by United States Letters Patent is:

In a percussion tool, a piston barrel of nonmagnetic material, a plurality of magnetic core members each comprising middle bars of magnetic laminations secured together, and end portions of substantially L-shaped members each comprising magnetic laminations secured together to form a unitary structure with an air gap between said end portions and middle bars, connecting blocks of non-magnetic material A5 bridging said air gap and welded to the middle and end portions, and welded joints between the sides of said members and barrel to hold the core structure in assembled position.

CARL S. WEYANDT. 

